C++ Type Conversion

C++ Type Conversion: In this tutorial, we will find out about the essentials of C++ type conversion with the help of examples.

C++ allows us to change over the data of one sort to that of another. This is known as type conversion.

There are two sorts of type conversion in C++.

1. Implicit Conversion
2. Explicit Conversion (otherwise called Type Casting)

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Implicit Type Conversion

The sort conversion that is done consequently done by the compiler is known as implicit type conversion. This type of conversion is otherwise called an automatic conversion.

Let us look at two examples of implicit type conversion.

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Example 1: Conversion From int to double

// Working of implicit type-conversion

#include <iostream>
using namespace std;

int main() {
   // assigning an int value to num_int
   int num_int = 9;

   // declaring a double type variable
   double num_double;
 
   // implicit conversion
   // assigning int value to a double variable
   num_double = num_int;

   cout << "num_int = " << num_int << endl;
   cout << "num_double = " << num_double << endl;

   return 0;
}

Output

num_int = 9
num_double = 9

In the program, we have assigned an int data to a double variable.

num_double = num_int;

Here, the int value is consequently changed over to double by the compiler before it is allowed to the num_double variable. This is a case of verifiable sort conversion

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Example 2: Automatic Conversion from double to int

//Working of Implicit type-conversion

#include <iostream>
using namespace std;

int main() {

   int num_int;
   double num_double = 9.99;

   // implicit conversion
   // assigning a double value to an int variable
   num_int = num_double;

   cout << "num_int = " << num_int << endl;
   cout << "num_double = " << num_double << endl;

   return 0;
}

Output

num_int = 9
num_double = 9.99

In the program, we have assigned a double data to an int variable.

num_double = num_int;

Here, the double worth is consequently changed over to int by the compiler before it is doled out to the num_int variable. This is likewise a case of a certain type of conversion.

Note: Since int can’t have a decimal part, the digits after the decimal point is shortened in the above example.

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Data Loss During Conversion (Narrowing Conversion)

As we have seen from the above example, change starting with one data type then onto the next is inclined to data loss. This happens when data of a bigger sort is changed over to data of a littler type.

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C++ Explicit Conversion

When the user manually changes data starting with one sort then onto the next, this is known as explicit conversion. This sort of conversion is otherwise called typecasting.

There are three significant manners by which we can use explicit conversion in C++. They are:

1. C-style type projecting (otherwise called cast notation)

2. Function notation (otherwise called old C++ style type casting)

3. Type conversion operators

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C-style Type Casting

As the name suggests, this type of casting is favored by the C programming language. It is also known as cast notation.

The syntax for this style is:

(data_type)expression;

For example,

// initializing int variable
int num_int = 26;

// declaring double variable
double num_double;

// converting from int to double
num_double = (double)num_int;

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Function-style Casting

We can also use the function like notation to cast data from one type to another.

The syntax for this style is:

data_type(expression);

For example,

// initializing int variable
int num_int = 26;

// declaring double variable
double num_double;

// converting from int to double
num_double = double(num_int);

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Example 3: Type Casting

#include <iostream>

using namespace std;

int main() {
    // initializing a double variable
    double num_double = 3.56;
    cout << "num_double = " << num_double << endl;

    // C-style conversion from double to int
    int num_int1 = (int)num_double;
    cout << "num_int1   = " << num_int1 << endl;

    // function-style conversion from double to int
    int num_int2 = int(num_double);
    cout << "num_int2   = " << num_int2 << endl;

    return 0;
}

Output

num_double = 3.56
num_int1   = 3
num_int2   = 3

We used both the C style type conversion and the function style casting for type conversion and showed the outcomes. Since they play out a similar assignment, both give us the same output.

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Type Conversion Operators

Besides these two type castings, C++ also has four operators for type conversion. They are known as type conversion operators. They are:

static_cast
dynamic_cast
const_cast
reinterpret_cast
We will learn about these casts in later tutorials

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Please feel free to give your comment if you face any difficulty here.

C++ Introduction